Cognitive (thinking) strategies and skills are the tools for all types of thinking and problem solving. Competence in them is hence needed for effective learning and problem solving. Research suggests that many learning difficulties of students are due to their not being sufficiently competent in them. This monograph illustrates the use of five important problem solving strategies that would lead to more effective problem solving not only in science courses but also in our daily lives. Lecturers/ instructors/students at high school and tertiary education institutions should find the monograph useful. Since many problems in this monograph do not need science concepts, parts of the monograph may also be used by people without a science background.